1. Field of the Invention
The invention relates to closure systems and methods for releasably sealing autoclaves and sterilizers. More particularly, the invention relates to a variable pressure, hydraulically actuated door clamping system for an autoclave or sterilizer door which is also self-locking. In addition, the invention relates to a variable pressure, hydraulically actuated system for positioning the autoclave door between open and closed positions and also vertically positioning the door so that the clamping system is engaged.
2. Description of the Prior Art
The autoclave and sterilizer art generally describes apparatus and methods for releasably sealing doors of autoclaves and sterilizers. The ability of a particular apparatus to effectively seal a sterilizer is critical because the apparatus must maintain the temperature and pressure environment within the sterilizer to insure that effective sterilization takes place. Ineffective sterilization may result in contaminated equipment or articles which are subsequently used for medical procedures. The contaminated equipment or articles may in turn cause infection in patients. In addition, autoclave or sterilizer sealing apparatus must be operable in a safe manner by the person using the apparatus.
Generally, conventional sealing apparatus rely on a compressible gasket or a pressurized fluid to provide an effective seal between the door and the chamber. U.S. Pat. No. 4,932,160 describes an apparatus for sealing an autoclave door which includes both the use of a compressible gasket and a pressurized fluid. The compressible gasket is located in a gasket channel, and once the autoclave door is moved to a closed position the pressurized fluid is pumped into the gasket channel and forces the compressible gasket against the door to provide an effective seal. Other patents teach similar sealing apparatus which rely on the use of a pressurized fluid to provide an effective seal between the door and chamber of an autoclave or sterilizer. For example, U.S. Pat. Nos. 3,694,962; 3,371,986; 4,335,075 describe apparatus of this type. It should be appreciated that apparatus which rely on a pressurized fluid to provide the seal between a door and a chamber will correspondingly require a system for pressurizing and depressurizing that fluid. This fluid pressurizing and depressurizing system increases both the complexity and expense of the apparatus.
Conventional apparatus which rely on compressible gaskets to provide a seal between a door and chamber suffer from failure due to creep or permanent set of the gasket. Furthermore, conventional compressible gasket systems typically require expensive and mechanically complicated equipment for compressing the gasket between the door and chamber. (See U.S. Pat. No. 4,469,335 at col. 1, lines 46-50). It is believed that these disadvantages associated with compressible gaskets system were overcome by the use of the pressurized fluid sealing type systems.
Conventional sterilizer and autoclave door opening, closing, and sealing systems also suffer from problems associated with loss of electrical or hydraulic power. For example, in some conventional systems the loss of electrical or hydraulic power may cause the clamping part of the system to release thereby unsealing the autoclave or sterilizer. This type of failure could be particularly dangerous if the autoclave or sterilizer is in a pressurized state. A more frequently occurring problem relates to the inability to operate the autoclave or sterilizer when electrical or hydraulic power is lost. In addition, conventional opening and closing systems may allow the door to inadvertently move and close over time due to leakage in the hydraulic system.
Moreover, conventional autoclave and sterilizer opening, closing, and sealing systems suffer from the disadvantage that the force exerted to open or close the door of the autoclave or sterilizer is constant. The use of a constant force for this purpose may result in injury to the operators or other persons in proximity to the autoclave or sterilizer due to the amount of force exerted by the door.